zero morpheme

例句：

1. 1. The zero morpheme is the smallest unit of language that can be combined to form words.
   零形态元素是语言中最小的单位，可以组合成词语。
2. 2. In mathematics, a zero morpheme represents an empty set or no value at all.
   在数学中，零形态元素代表一个空集或没有任何值。
3. 3. The zero morpheme is often used in programming languages to indicate that a variable has no value.
   在编程语言中，零形态元素通常用于表示变量没有值。